a - Click System Settings, Click Language Support

you may be prompted to install support for current languages

b - Ensure that Keyboard input method system: is set to IBus

c - Click Install / Remove Languages

d - Choose Chinese (simplified) and/or Chinese (traditional)

e - (ubuntu 16.04, 18.04, 20.04) - Click Apply

LogOut > LogIn

f. Click System Settings, Click Language Support

g. Click Input Sources, add Intelligent Pinyin

LogOut > LogIn